Argentina and Brazil could see Saturday's friendly in Beijing cancelled due to smog in the Chinese capital.
The two teams have been confined to their hotel rooms after the air quality in the city deteriorated rapidly, and Brazil team doctor Rodrigo Lasmar has revealed that the players have only left their base for training.
Lasmar told Esportes Futebol: "One of the pieces of advice that those responsible for pollution control give is that people should stay indoors and this is what we have done.
"Our athletes stay inside the hotel and only go out for training. Out of every 24 hours, they spend 22 inside the hotel."
The conditions aren't expected to improve until sometime on Saturday, with the game scheduled to start at 8.05pm, local time.